CAI — The First Solid Matter in Our Solar System

precipitated directly from the swirling nebular gas of our solar system as it formed, at 1,400° near the Sun, CAI (Ca–Al-rich Inclusion) grains proliferated at the very beginning, literally setting the clock for the start of our Solar System 4.567 billion years ago.

From the CV3 Carbanaceous Chondrite, NWA 8722